He had escaped a kidnapping attempt in August, when he saw masked gunmen approaching his pharmacy and fled. He expected them to return, knowing that Lebanon’s security forces couldn’t help.

Hostage-taking of wealthy businessmen in Lebanon has risen more than seven-fold in an unlikely effect from Syria’s civil war. Security officials say gangs who once made their money smuggling fuel and contraband through the porous Syria-Lebanon border have watched their trade wither because of the violence, so they are turning to kidnapping to make a profit.

Lebanon is suffering multiple woes from the war next door. The tiny country, with a population of 4.5 million, has been flooded with an estimated 1 million Syrians fleeing the conflict. Also, tensions between its Sunni and Shi’ite communities have spiked, sometimes exploding into deadly clashes, mirroring the sectarian hatreds in Syria, where Sunnis largely support the rebellion, and Shi’ites and the Alawite sect — an offshoot of Shiism — back President Bashar Assad.

In the latest violence, a Sunni sheik, Saad El-Deen Ghieh, was shot to death in his car Tuesday by gunmen in the northern city of Tripoli, scene of frequent clashes between Sunnis and Alawites in connection with Syria’s war.

In contrast, the kidnapping wave — a more indirect repercussion — illustrates the multiple, unexpected ways that Lebanon, with its fragile hold on security, is vulnerable to the turmoil across the border. There are fears the problem could spread — and that abductions could spread beyond criminal activity and into political motives — as Syria’s war, which began in March 2011, continues.